Process of producing indoxylic compounds.



UNITED STATES PATENT .OFFICE.

HANS LABHARDT, OF MANNHEIM, GERMANY, AssI GNoR TO BADISCHE ANILIN1& SODA FABRIK, or LUDWIGSHAFEN ON-THERHINE, GERMANY, A CORPORATION.

PROCESS OF PRODUCING INDoxYLIo comrormns.

Specification of Potter; Patent.

I Patented June 23, 1908.

v Application filed February 26, 1907. Serial No. 359,511.

To all whom it may concern:

Be it known that I, HANS LABHARDT, doctor of hilosophy and chemist, citizen of the Swiss epubl1c,:residing at Mannheim, Germany, have invented new and useful Im- .provements in the Production of Indoxylic Compounds, of which the following is a speci fication. V i

The method hitherto usually employed for the production of indoxylic compounds from henylglycin, or the homologues, or anaog'ues,'thereof,"or derivatives thereof, has consisted in treating such 'phenylglycin, homologue, analogue, or derivative, with an alkaline condensing agent, such, for instance, as alkali oxid, sodium alcoholate, and sodamid. ployed to bring about the indoxylic ring ormation, sulfonation generally takes place at the same time, so that indigo sulfoacid is obtained instead of indigo and the undesirable operation of eliminating the sulfoacid group, in order to produce the more valuable indigo, is necessary.

In the specification ofthe lapsed French Patent No. 310,599it is stated that, by"

treating the potassium salt of acetylphen lglycin with, for instance, phos horus oxychi rid, and then'treating the c orid of acetylphenylglycin, thus obtained, with aluminium chlorid,indoxyl can be Obtained. On working vaocordingto the directions given in the,

said specification vI have been unable, however, to obtain any indoxyl, or indigo, but I have found'that if, instead of treating the chlorid of .acetylphenylglycin "with aluminium chlorid, the acetylphenylglycin itself be treated with aluminium chlorid, or other aluminium haloid, the ring formation takes place easily and indoxyl is obtained either as such or in the acylated form. The reaction should preferably be carried out-'in the absence of atmospheric air, for instance; it may be carried out in an atmosphere of hydrogen, or nitrogen, or carbon dioxid, or other indifferent gas, or in 'vacuo'.

Instead of acetylphenylglycin itself, the I homologues, analogues, and derivatives of these compounds (such for instance as their salts and esters) can be employed, and aluminum bromid, or aluminium iodid, can be used instead of aluminium chlorid.

, The following examples will serve to illus trate further the nature of my invention and how it can becarried into practical efiect,

When fuming sulfuric acid is, em-

I but my invention is not confined to these ex-- amples nor to the e nations given therein. The parts are by weight. 7

Example 1. Mix thoroughly together equal'parts of dried and finely powdered acetylphenylgl cin and 1 freshly prepared finely ground alilminium chlorid. Introduce the mixture into'a suitable vessel, for instance an enameled iron vessel, and displace the air by means of dry hydrogen and heat in ametal, or oil, bath so that the tem erature of the bath reaches about two hun red and fifty (250) degrees centigrade. The reaction mixture soon melts to a red li uid while hvdrochloric acid is evolved. W enthe evolution is finished, allowthe melt to cool, and

introduce it intoboiling dilute caustic soda solution, whereupon any'acetylindoxyl is converted into indoxyl. If it be so'desired, air can be assed through the solution, Whereu on in igo is formed. The indoxy-l is proba 1y formed according to the equation (200), to tWo hundred and twenty (220), de- I grees centigrade.- The mass' gives rise to a thick red 11 uid, while hydrochloric acid is evolved. After about thirty, (30) minutes the gas-evolution-is complete, then work up themelt as described in the fore oing example. The aluminium chlorid w ich sublimes onto the cooler parts of the vessel can be used in a further operation, The reaction which takes place can be represented by the equation son om ucoon .oH oooH+A1o1 Ncoon Example 3. well together one (1) part of the potassium salt of acetylphenylglycin and three'(3) arts of anhydrous alumlnium chlorid (both elypowdered), and heat the BCH C H I mixture for thirty (30) minutes in vacuo at a tempreature of from two hundred and degrees centigrade.

\ hydrous aluminium chlorid, in small portions" at a time, into one ,(1 partof the ethyl ester thirty (230), to two hundred and forty (240), A vigorous reaction takes place andthe mixture melts, yielding a red liquid. Allow the melt to cool, and" Work up in the manner described in the foregoing Example 1. The reaction which takes place can be represented by the equation Example 4. Introduce two (2) parts of an- Instead" of using acetylglycins, other *glycins, which the amido group contains ,lents of the free glyoins.

The reaction other fatty, 'or aromatic, acid radicals,'.can be em loyed, and glycins'of the benzene, or naphthalene, series may be used, so that the eneral formula of the compounds which can eused accordingto this invention is ArylNAc.CH .G/QOH,

and of course, as aforesaid, the derivatives,

such'as the salts and esters, of these compounds can be em loyed and for-the purposes of this invention t ese derivatives'are equlvacorresponding indoxyl either as such orin its acylated form is obtained and this can be converted into the corres onding indigo dye in the usual, orany suitable, manner. If in the above examplesthe aluminium chlorid be replaced by .an equivalent quantity of aluminium bromid, the reaction proceeds ina similar manner. Now What I claim 1s: r

- 1; The process of producing in'doxylic compounds by reacting on an acylated arylglycln with aluminium haloid.

2.. The process of producing indoxylic compounds byreactin? on acetylphenylglycin with aluminium ch orid.

In each case the In testimony whereof I have hereunto'set my hand in the presence of two subscribing witnesses. I

- Witnesses: v

ERNEST EHRHA T," v H. W HARRIS.

- HANS LABHARDT. 

